The development of microwave cooking has had an enormous impact on food preparation. The high speed with which cooking occurs and the broad array of materials suitable for use in microwave ovens has created an ever-increasing demand for economical, simple, disposable, containers which, when used in a microwave oven, duplicate as closely as possible the cooking results of a conventional oven. The introduction of relatively low cost and reliable microwave interactive materials (sometimes referred to as susceptor materials) has made microwave cooking even more attractive for those food items which require crisping or browning with cooking.
To this end, various specialized packages have been developed to achieve microwave browning or crisping of the food items contained therein. In the case of a pizza-type product, this means that the bottom and side crust must be crisp and its top must be warm and soft. An early concept is suggested in U.S. Pat. No. 4,190,757 to Turpin et al. that utilizes a lower susceptor sheet spaced from the bottom wall of the microwave oven onto which the lower crust portion of a pizza-type product is supported so that the crust portion is heated to a high temperature causing browning and crispness adjacent the lower surface of the crust. Other benefits of the Turpin package are that it is disposable and that it can be used both as a shipping carton suitable for display in a supermarket and as a heating dish to be used by the ultimate consumer. See also, U.S. Pat. Nos. 4,592,914, 4,505,391 and 4,096,948 to Kuchenbecker and U.S. Pat. No. 4,836,383 to Gordon et al. These packages, however, generally have a complicated construction that adds to the manufacture and assembly costs.
In the case of refrigerated and, especially, frozen food products, a substantial volume of water and grease in gaseous form may be released during exposure to microwave energy, which must escape from the package in order to prevent the production of soggy or greasy food. Accordingly, many presently known packages provide for venting. For example, some packages utilize open-ended sleeves during cooking (e.g., U.S. Pat. No. 4,891,482 to Jaeger et al.), while others have vented end portions (e.g., U.S. Pat. No. 4,567,341 to Brown). Again, however, these packages generally have a complicated construction.
Another known carton has a susceptor sheet in the bottom of the carton and has a scored top flap that is sufficiently separable from the remainder of the package to permit it to be folded under the bottom of the carton during cooking in a microwave oven. With this carton, however, the folded top flap merely forms another layer of package material between the bottom of the carton and the microwave oven floor, which may result in heat loss to the oven floor. Additionally, the folded top flap raises one end of the package higher off the microwave oven floor than the other end, which may result in nonuniform cooking. Also, the top of the food item is unshielded during cooking, which in many instances is undesirable.
Despite the proliferation of specialized microwave heating packages, it should be appreciated that there is still a need for an improved package that is economical, simple and disposable and which, especially in connection with a pizza-type product or a bakery item, results in a high quality crisp crust product that is easily accessible and removable. The present invention satisfies this need.